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Climate and sea-level variability during the past ~ 2000 years

Andrew Kemp (Tufts University)
Fri, November 10, 10:30am - 11:30am

Video broadcast

Host: Fred Taylor

Abstract: Common Era relative sea-level trends on the margins of the North Atlantic Ocean vary through time and across space as a result of simultaneous global (basin-wide)-, regional- (linear and non linear), and local-scale processes. A growing suite of relative sea-level reconstructions derived from dated salt-marsh (and mangrove) sediment on the Atlantic coast of North America provides an opportunity to quantify the contributions from several physical processes to Common Era sea-level trends. In particular, this coastline is susceptible to relative sea-level changes caused by melting of the Greenland Ice Sheet and redistribution of existing ocean mass on timescales of days to centuries by evolving patterns and strengths of atmospheric and oceanic circulation. Spatio-temporal analysis shows that glacio-isostatic adjustment was the primary driver of sea-level change. The global signal is dominated by the onset of anthropogenic sea-level rise in the late 19th century, which caused the 20th century to experience a faster rate of rise than any of the preceding 26 centuries. Differentiating between regional non-linear and local-scale processes is challenging using an inherently sparse network of reconstructions. However, we show that sites south of Cape Hatteras have sea-level histories distinct to those from more northward locations and propose that this spatial pattern is best explained by dynamic processes.